Time of Flight Diffraction (TOFD)

Time of Flight Diffraction method uses two connected angled probes (transmitter-receiver) set at opposite areas of the area to be tested.
TOFD is a sensitive and accurate NDT method for testing material discontinuity, as in weld defects.
The transmitter probe sends an ultrasonic signal into the part to be measured and the receiver picks up the signal on the other side.
A diffraction of the ultrasonic sound wave from the top and bottom tips of the fault indicate through-wall crack-like-defects and can be accurately measured.